Automobile driveshafts as used between the transmission and differential of rear wheel drive vehicles transmit vibrations occurring in the differential, or transmission, resulting in noisy operation. Also, with automatic transmission, clunking and sudden torque transfer vibrations often occur during shifting between forward and rear gear selections.
It has been discovered that many of the objectionable vibrations occurring in vehicle drive train systems can be eliminated by damping, and various types of dampers have been developed for this purpose. For instance, vibration damping in resilient elements are shown in U.S. Pat. Nos. 3,878,695; 4,197,759 and 4,406,640.
Attempts have been made to dampen vibrations in driveshafts and drive lines as shown in U.S. Pat. Nos. 2,857,974 and 4,020,651. However, previous torque transmitting couplings of this type have not been able to effectively withstand the highly adverse operating conditions wherein high torques must be transmitted, and conventional systems wherein elastomers are bonded to metal components are not capable of achieving the dependability required in this environment.
It is an object of the invention to provide a driveshaft coupling capable of damping vibrations over an extended frequency range, and wherein the coupling is capable of transmitting high torque forces without adverse wear and deterioration.
Another object of the invention is to provide a driveshaft coupling suitable for vehicle use capable of absorbing vibrations over a wide frequency range wherein elastomer elements are utilized and torque is transmitted by compression of the elastomer.
Yet another object of the invention is to provide a driveshaft coupling utilizing compressible elastomer elements for vibration damping purposes and lost motion metal-to-metal surfaces are employed to transmit torque upon predetermined elastomer deformation occurring.
A further object of the invention is to provide a driveshaft coupling of concise configuration capable of damping vibrations and wherein the coupling has a configuration and size similar to previously employed similar components having no vibration damping capabilities.
In the practice of the invention, an elongated drive member comprising a portion of a universal joint includes an elongated rectangular portion of a square transverse sectional configuration. This rectangular section is in radial alignment with a tubular driven member having a square transverse section and the flat surfaces of the drive and driven members are in spaced parallel relationship. An elastomer element or pad is interposed between each set of parallel opposed flat surfaces. Preferably, the elastomer is under precompression.
Torque is transmitted from the drive member to the driven member by the tendency of the dimensions between the opposed surfaces to change, which will compress portions of the elastomer and thereby transmit torque. Accordingly, the torque is transmitted only through elastomer under compression eliminating any tendency for the elastomer to be subjected to tension forces.
Metal-to-metal engagement between the drive and driven members occurs upon excessive torque forces being produced. In such event a "lost motion" exists relative to the metal-to-metal drive between the drive and driven members such that such positive engagement occurs only after maximum compression of the elastomers occurs.
The construction of the coupling is such that similar torque transmitting capabilities exist in either direction of rotation of the drive and driven members, and the coupling is so fabricated as to be easily assembled, and readily manufactured at reasonable cost.